I'm not allowed to smoke in the house, so I can pretty much only smoke while I'm driving. I often spend all day in the jeep, driving all over VA, and I don't listen to much music anymore. I find that if there is music playing, and I'm familiar with it, my brain just sort of shuts off, and I get mild "highway hypnosis". But if I'm listening to something I've never heard before, I stay more alert. So I listen to spoken word podcasts almost exclusively while driving.
My list of podcast subscriptions is as follows:
CarStuff
Common Sense with Dan Carlin
Doug Loves Movies
Comedy Death-Ray Radio
Culturetopia
Friday Night Comedy from BBC4
Fresh Air with Terry Gross
TED Talks
Stuff you Should Know
Real Time with Bill Maher
Judge John Hodgeman
KCRW's Film Reviews
Mark Kermode and Simon Mayo's Film Reviews from BBC5
NPR's 7am news
NPR's Intelligence Squared debates
NPR's Story of the Day
NPR's Sunday Puzzle
Wait Wait, Don't Tell Me
The Onion
PRI's The World Geo Quiz
Shut Up, Wierdo
The Bugle Podcast
This American Life
Most of these are short (~5 minutes), so I can churn through 20 or so in a day. Some others are a bit longer (Fresh air is usually an hour long, as are Comedy Death Ray, Wait Wait, and Kermode and Mayo's Film Reviews). Point is, I never run out of stuff to listen to, and it's always something I've never heard before.